1. Field of the Invention
The present invention relates to a torque adjusting type hinge adapted to control the angles at which a display unit or swinging cover a notebook-type personal computer or of a word processor is tilted when in use.
2. Description of the Related Art
When using an electronic instrument such as a notebook type personal computer or the like, it is necessary to hold the display unit of the electronic instrument at an appropriate tilting angle which the user may require. Heretofore, it has been known to employ a hinge using its frictional resistance for preventing the display unit from freely rotating.
In one example of such conventional hinge using the frictional resistance, a resilient member assuming having a pipe-like shape is inserted into a cylindrical base member with one of its opposite ends open and the other closed to form its bottom; a small-diameter portion of a stepped-diameter pin element is inserted into the resilient member and is press-fitted therewith so as to enlarge in the diameter of the resilient member, causing the resilient member to have its outer peripheral surface press-fitted to an inner peripheral surface of the base member. In other words, the resilient member is inserted into the base member in a manner such that the resilient member is prevented from freely rotating relative to the base member because of the presence of a frictional resistance between the resilient member and the base member. The stepped-diameter pin element has an end of its large-diameter portion connected with a display unit having a base member fixedly mounted on a main body of the electronic instrument. Due to such arrangement, the frictional resistance produced between the base member and the resilient member permits the user to hold the display unit in a stationary tilted position.
The conventional hinge mentioned above is, disadvantageous in that the press-fitting degree of the pin element to the resilient member is too apt to vary. This leads to variations in frictional resistance and makes it difficult to keep the holding power of the pin element constant. As a result, it is difficult to mass-produce a product with constant characteristics. Furthermore, the conventional hinge has the disadvantage of not being durable, because of the lack of means for compensating for wear occurring in the resilient member from use, causing a decrease in the frictional resistance between the resilient member and the pin element.
Attempts have been made to solve the problem of variations in frictional resistance as well as deterioration or decrease in frictional resistance over time. Further consideration is also proposed in another conventional torque adjusting type hinge as in Japanese Utility Model registration No. 253005. According to this arrangement, a pin element is provided to co-operate with a holder member, which assumes a sleeve-like shape for rotatably holding the pin element rotatably therein relative to the holder member. The holder member has one of its opposite ends open and the other is closed to form its bottom. A resilient member, is interposed between the pin element and the holder member to produce a frictional resistance when the pin element is rotated relative to the holder member. A compression spring is provided for axially urging the resilient member in a longitudinal direction of the pin element.
However, this conventional torque adjusting type hinge compression spring is also disadvantageous. This construction is large in size, and therefore requires a large storage and installation space in the electronic instrument. This limits the field of application for the conventional hinge and represents another problem inherent in the conventional hinge.
In Japanese Patent application Laid-Open No. 2004-169360, there is proposed another torque adjusting type hinge. This conventional hinge employs a compact mechanism for adjusting a frictional torque therein. More specifically, this type of conventional hinge construction has a support member mounted on a main body of the instrument; and a rotary pin, is rotatably mounted on a support member having a plurality of inclined friction plates, which are tiltably mounted thereon. A forcing screw is employed for urging the inclined friction plates to tilt.
However, this type of the conventional hinge is also disadvantageous, in that the rotary pin exhibits considerable wear while in use. This is due to the presence of a bite-type interference occurring between the rotary pin and its counterpart,—namely, wall surface of an annular frictional portion of each of the inclined friction plates. The annular frictional portion is integrally formed with a pressure receiving portion of each of the inclined friction plates, whereby the pressure receipt receiving portion is urged by the forcing screw in the hinge as it is advanced.